Setting The High Set Point; Setting The Low Set Point; Alternate Set Point Adjustment Procedure - Fisher 4660 Instruction Manual

Type 4660
7. Continue with the appropriate procedures described
below. Replace the cover and cover screws after all
adjustments are completed.

Setting the High Set Point

To ensure that full output pressure will
be indicated during the following steps,
make sure the previous six steps of the
Preliminary Adjustments portion of this
section have been completed before
proceeding.
WARNING
To avoid personal injury or property
damage caused by a sudden release of
pressure, do not exceed the Bourdon
Tube rating (see tables 2 and 3).
To set the high set point pressure, perform the follow-
ing three steps:
1. Adjust the external pressure source to the desired
high set point pressure.
2. Check that full output pressure is being registered
by using a pressure gauge installed in the output pres-
sure line or by using the optional output indicator (key
88). The optional output indicator shows a green color
when the output pressure is at full pressure and black
when the output pressure is at zero.
3. Slowly turn the HIGH SET knob counterclockwise
until the desired high set point is obtained. The high
set point is obtained when the output pressure of the
pilot has changed from full output to zero.
4. Lock the locking disk (key 69).

Setting the Low Set Point

To ensure that full output pressure will
be indicated during the following steps:
Make sure that the first six steps of
the Preliminary Adjustments portion of
this section have been completed before
proceeding, and
Make sure the difference between
the high set point pressure and the low
set point pressure is greater than or
equal to the appropriate Set Point P
value specified in tables 2 and 3.
8
Note
Note
MIN
To set the low set point pressure, perform the follow-
ing three steps:
1. Adjust the external pressure source to the desired
low set point pressure.
2. Check that full output pressure is being registered
by using a pressure gauge installed in the output pres-
sure line or by using the optional output indicator (key
88). The optional output indicator shows a green color
when the output pressure is at full pressure and black
when the output pressure is at zero.
3. Slowly turn the low set point knob (key 67) clock-
wise until the low set point is obtained. The low set
point is obtained when the output pressure of the pilot
has changed from full output to zero.
4. Lock the locking disk (key 69).
Alternate Set Point Adjustment
Procedure
This procedure may be used to closely approximate
the desired high and low set points when no external
pressure source is available to simulate process pres-
sure. If the pilot does not have the optional output indi-
cator (key 88), provide a means of indicating the out-
put pressure. Refer to figure 5.
For high-low constructions, perform steps 1 through 7.
For high-only constructions, perform steps 1, 2, 4, and
5. For low-only constructions, perform steps 1 through
3, 6, and 7.
Make sure the first 6 steps of the Prelim-
inary Adjustments portion of this sec-
tion have been completed before pro-
ceeding.
1. Refer to the warning at the beginning of the Operat-
ing Information section. Make sure the Bourdon tube
contains no pressure.
2. Connect supply pressure to the pilot.
3. Turn on the supply pressure. To check that the sup-
ply pressure is on, press the SUPPLY TEST button in
the cleanout assembly (key 54) until a flow sound is
heard.
4. Turn the LOW SET knob counterclockwise until it
has reached the end of its travel.
5. Turn the HIGH SET knob counterclockwise until the
high set point pivot just comes in contact with the flap-
per. The pilot should have full output pressure (green
indication on the optional output indicator).
6. Refer to table 5 and turn the HIGH SET knob clock-
wise to correspond to the desired set point value. For
example, with a 100 psig (690 kPa) Bourdon tube, turn
the knob five revolutions for a desired high set point of
60 psig (415 kPa).
Note